Question: Simplify the following expression: $p = \dfrac{7}{4z} + \dfrac{1}{9z}$
Answer: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $4z$ and $9z$ $\lcm(4z, 9z) = 36z$ $ p = \dfrac{9}{9} \cdot \dfrac{7}{4z} + \dfrac{4}{4} \cdot \dfrac{1}{9z} $ $p = \dfrac{63}{36z} + \dfrac{4}{36z}$ $p = \dfrac{63 +4}{36z}$ $p = \dfrac{67}{36z}$